You do not see ultraviolet light or hear infrasound because you do not have sensory receptors that can detect these as light and sound. When there is or is not ultraviolet light or infrasound, you do not receive a signal of 0 or 1 in your light and sound sensors but there is (for lack of a better word) a null signal. A lack of means to detect something does not communicate that zero or any other amount of that something is present — it is simply obliviousness without necessarily knowing that there is obliviousness.